1. Statement of the Technical Field
The inventive arrangements relate to RF interference management, and more particularly to RF interference management for commercial cell phone devices.
2. Description of the Related Art
One or more radio transceiver devices can be integrated into a personal communication device such as a cellular telephone. For example, Bluetooth, WiFi, cellular and GPS radios can all be included within a single personal communication device. The various radios integrated into a single personal communication device can be managed to permit their apparent simultaneous operation without harmful interference. The operation is said to be apparently simultaneous insofar as the various radios may appear from a user perspective to be operating simultaneously.
The need for radio management operations frequently arises due to the relationship of the frequencies on which one or more radio devices within a single device are communicating. For example, Bluetooth and WiFi are deployed in the same spectrum at 2.4 GHz. Some cellular bands are adjacent to Bluetooth, WiFi, and GPS frequency spectrum. Moreover, algebraic frequency relationships are known to exist between allocations of one radio and another radio. Even small non-linearities cause transmitters at one frequency to generate spurious energy at another frequency. Typically the spurious emissions will appear at frequencies defined by: ax+/− by where a and b are small integers and x and y are radio operational frequencies. Other interference scenarios can arise where radio transmissions from one radio of the personal communication device generate noise energy that extends beyond the intended bandwidth of the signal. This noise energy can interfere with communications operations of other radios included on the device.
In general, cellular radios can be characterized by certain attributes that drive interference management techniques: For example, providers promise users only commercial quality service and it is therefore accepted that reduced radio performance may occur during times of simultaneous operation. Also, apparent (rather than actual) simultaneous radio operation is acceptable. Perhaps most importantly, interference management can be adequately provided internally of the device itself since it has advance knowledge of which radios are present and can include control and processing resources that facilitate management of the various radios which are present.
In contrast to conventional commercial cellular communications, the LMR communication equipment used by first responders (e.g., policemen and firemen) must deliver mission critical quality of service. For these users, reduced radio performance due to interference is not acceptable. Also, from the standpoint of the first responder, a loss in simultaneous operation may be acceptable if necessary to maintain the reliability of mission critical communications.
Cellular telephones are often used in close proximity to LMR radios used by first responders. In some scenarios one or more radio transceivers included on the cellular telephone may operate in the same frequency range or a frequency range adjacent to one that is used by the LMR equipment. Without a mechanism to effect mitigation of interference, critical or high priority messages directed to either the cellular transceiver or first responder radio device can be masked by lower priority messages to the other device. Ultimately, the lack of communication management can prevent important messages from achieving required performance and reliability standards. Device users cannot be expected to anticipate when interference is likely to occur, and cannot be expected to control the severity of such interference effectively In fact, the potential for interference is increasing due to a focus on efficient use of spectrum. The problem is often compounded because users are not aware when a message has been masked due to interference.